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Everything posted by SH_MM

Well, if you include TUSK as armor kit for the Abrams, then you also have to include the different Theatre Entry Standards (TES) armor kits (three versions at least) of the Challenger 2. The base armor however was most likely not upgraded.
The Leclerc is not geometrically more efficient. It could have been, if it's armor layout wasn't designed so badly. The Leclerc trades a smaller frontal profile for a larger number of weakspots. It uses a bulge-type turret (no idea about the proper English term), because otherwise a low-profile turret would mean reduced gun depression (breech block hits the roof when firing). There is bulge/box on the Leclerc turret roof, which is about one feet tall and located in the centerline of the turret. It is connected to the interior of the tank, as it serves as space for the breech block to travel when the gun is depressed. With this bulge the diffence between the Leopard 2's and Leclerc's roof height is about 20 milimetres.
The problem with this bulge is, that it is essentially un-armored (maybe 40-50 mm steel armor); otherwise the Leclerc wouldn't save any weight. While the bulge is hidden from direct head-on attacks, it is exposed when the tank is attacked from an angle. Given that modern APFSDS usually do not riccochet at impact angles larger than 10-15° and most RPGs are able to fuze at such an angle, the Leclerc has a very weakly armored section that can be hit from half to two-thirds of the frontal arc and will always be penetrated.
The next issue is the result of the gunner's sight layout. While it is somewhat reminiscent of the Leopard 2's original gunner's sight placement for some people, it is actually designed differently. The Leopard 2's original sight layout has armor in front and behind the gunner's sight, the sight also doesn't extend to the bottom of the turret. On the Leclerc things are very different, the sight is placed in front of the armor and this reduces overall thickness. This problem has been reduced by installing another armor block in front of the guner's sight, but it doesn't cover the entire crew.
The biggest issue of the Leclerc is however the gun shield. It's tiny, only 30 mm thick! Compared to that the Leopard 2 had a 420 mm gun shield already in 1979. The French engineers went with having pretty much the largest gun mantlet of all contemporary tanks, but decided to add the thinnest gun shield for protection. They decided to instead go for a thicker armor (steel) block at the gun trunnions.
Still the protection of the gun mantlet seems to be sub-par compared to the Leopard 2 (420 mm armor block + 200-250 mm steel for the gun trunion mount on the original tank) and even upgraded Leopard 2 tanks. The Abrams has a comparable weak protected gun mantlet, but it has a much smaller surface. The Challenger 2 seems to have thicker armor at the gun, comparable to the Leopard 2.
Also, the Leclerc has longer (not thicker) turret side armor compared to the Leopard 2 and Challenger 2, because the armor needs to protect the autoloader. On the other tanks, the thick armor at the end of the crew compartment and only thinner, spaced armor/storage boxes protect the rest of the turret. So I'd say:
Challenger 2: a few weakspots, but no armor upgrades to the main armor
Leclerc: a lot of weakspots, but lower weight and a smaller profile when approached directly from the turret front
M1 Abrams: upgraded armor with less weakspots, but less efficient design (large turret profile and armor covers whole turret sides)
So if you look for a tank that is well protected, has upgraded armor and uses the armor efficiently, the current Leopard 2 should be called best protected tank.

M1 Abrams' TUSK belly plate is made of spaced aluminium plates and mainly works thanks to its massive thickness, reducing ground clearance by up to 11.5 inches (292 mm). AFAIK there is no other material, at least a photo of the belly plate in the TB 9-2350-264-12&P-1 shows no other materials.
The Leopard 2A6M, Boxer, Puma and other German AFVs use mine protection kits from RUAG, which are made of composite plates. The outermost layer is a steel plate, but it also includes on or more layers of plastic fibre to absorb the energy. In case of the Leopard 2A6M, the belly plate reduces ground clearance only by 50-100 mm, but is supposed to provide the same level of protection as the TUSK's much thicker spaced aluminium solution... however the Leopard 2A6M's plate is heavier. In case of the Puma IFV, the mine protection consists of two sandwich plates with more than 100 mm empty space between them.
RUAG's mine protection system. In theory it might also include ceramic materials against EFP mines, at least IBD Deisenroth is offering this as part of its AMAP-M anti-mine armor.

The British had some odd ideas about main battle tanks, although they wanted their MBT-80 to be more advanced in some aspects than the Challenger 2 currently operated by the British army...
The lack of an indendepent sight for the commander was disliked
The laser rangefinder of the M1 Abrams was incompatible with the thermal imager (?)
For some reason the British military thought it was a bad idea to integrate daysight and thermal imager into a unitary optic
The M1's fire control system resulted in a low hit probability (confirmed by statemens from US and German sources regarding the comparative trials of XM1 & Leopard 2AV)
The armor of the M1 Abrams could be penetrated at ranges of 4,000 m by the 125 mm gun according to British estimates
Storing ammo below the turret ring is/was seen as better than having a separated ammunition compartment at the rear of the turret because some US test proved that it might not always work with 105 mm ammo and wasn't tested with 120 mm; also the blast door needs to be open for reloading (silly complaint)
Leopard 2's protection was "imbalanced" (sounds like the same complaint of the US military - too little side armor) and insufficient to stop a 125 mm APFSDS round (est. penetration 445 to 460 mm steel at 1,000 m according to the document)
Shir 2 (that became the Challenger 1) was too heavy and also underpowered
British believed it was impossible to modify XM1 Abrams' armor to stop 125 mm APFSDS ammo
The drawing is from a 1975 patent by Krauss-Maffei. At this time the Leopard 2AV was being designeed. The patent topic are different ways to mount special armor in a main battle tank in order to allow replacing damaged armor modules, allow easier upgrading and allowing to completely remove the armor modules (which Krauss-Maffei suggested for traveling during peace time).
The patent suggest three ways of mounting armor:
mounting armor plates using screws (as done on the M1 Abrams)
using armor elements that fit into a cavity and together (like the Z-shaped ones) without any sort of additional attachment
putting the armor elements into "cages" or "boxes" with rubber-lined edges. The rubber-lined "cages" then are inserted with pressure into the cavities
The patent menions that the Z-shaped layout would provide most protection but also requires most space. It is not mentioned what the armor elements are made of (only that they ideally use metal to allow easier mounting). As far as I understand all these drawings are placeholders and do not represent actual tanks or actual armor arrays.
We know that all fully-assembled Leopard 2AV prototypes in the United States did not include special armor, only weight demonstrators. The special armor was send as armor modules for ballistic testing, which were only connected to a mock-up hull and turret. If they had already decided how this special armor would be mounted or not is unknown to me.
IMO the most likely variant is the upper one (Fig. 7 and Fig. 8), i.e. the armor is mounted in boxes or cages. This would explain the box-shaped turret, makes replacing armor easier and fits to the drawings from Sweden. However I think that the actual armor might look closer to the Z-shaped arrangement form Fig. 5 (there is no reason why it should be impossible to mount the Z-shaped armor elements at different angles in a cage/box). The method using bolts seems to be the least likely, because the bolts would be visible from the outside, but only the smaller bolts holding the cover plate are visible on the Leopard 2AV and early batch Leopard 2 tanks - if the bolts were used, the coverplate would look like this:

So we don't really know if these values are actually representing the Leopard 2's turret armor or are from some other file (camera instruction manual)?
If these protection values would be representing the actual Leopard 2 and if these were actually based on tests with the 120 mm DM33/JM33 ammunition, then it most likely would mean that the Leopard 2 would reach a (slightly) higher protection level against older types of APFSDS ammunition. The 120 mm DM33 APFSDS was specifically optimized to defeat multi-layered armor, against which older designs of APFSDS were found to be rather insufficient. According to a patent from Rheinmetall, a special tip design developed in the mid-1980s allows to increase the penetration against multi-layered armor, specifically such armor designs with "bouncy"/elastically mounted steel plates. The NERA arrays used on the Leopard 2 could be described as such armor - the German text speaks of "komplizierten Mehrschichtpanzerungen" ("complicated multi-layered armor arrays") and "federnd aufgehängten Panzerplatten" ("resiliently mounted armor plates"). The moving metal plate(s) of a NERA sandwich can be described as "Federblech" or "Beulblech" in German, with the armor of the Leopard 2 being called "Beulblechpanzerung" (bulging-plates armor) and "Lamellenpanzerung" (the latter term is used by the Austrian Bundesheer).
According to conservative estimations during the development of this new tip design, the penetration performance of the APFSDS ammunition could be increased by more than 10% against certain special armor arrays. So a measured protection value of 380 mm RHAe - if this reflected the Leopard 2's claimed protection against the 120 mm DM33 APFSDS - could very well be 400-440 mm steel-eqivalent protection against older rounds such as 120 mm DM23, Zakolka, Vant, Mango, etc.
However I don't think it is very likely, that the 120 mm DM33 ammunition was used for the data delivered to Japan. The 120 mm DM33 entered service in 1987 with the West-German Bundeswehr, which would be the last stage of the Type 90 development. I suppose the performance data of the Leopard 2 tank was requested before spending several million USD (or an equivalent sum of Yen) on the development of a new tank. Do you know when the data for the Leopard 2 was requested by Japan?

You can see the armor thickness in the photo above. This is the Challenger 2 tank located at the Bovington Tank Museum.
Does it specify how the armor protection was measured? I.e. what type of ammunition was used to establish the protection level? Is this the minimum/average/maximum protection along the frontal arc or when direclty hit at the front? Is the value "50%" related to this (e.g. is this the protection achieved on 50% of the tank's surface)?
The Swedish documents suggest that the Leopard 2 with the original armor package has at least 300 mm steel equivalent protection vs KE at ~63% of its surface, at least 340 mm steel equivalent protection vs KE at 50% and at least 400 mm steel equivalent protection vs KE at 20% of the surface. The Japanese data seems to confirm this, but there still should be some places with at least 400 mm vs KE.

No, it wasn't an argument about the suspension. The article published in the ARMOR magazine talked about the available net horsepower at the drive sprockets - so the suspension and cross-country are not part of the equation. I.e. Richard M. Ogorkiewicz wrote in "Technology on Tanks" (published in 1991) that "in general" only up to 70% of the actual engine output are available at the drive sprockets. The author of the article in the ARMOR magazine cites this statement and claims that the Merkava 3's powerpack has a 71% efficiency, implying (because the statement referencing R. M. Ogorkiewicz said "not more than 70%") that the performance delta between the other tanks with 1,500 hp engines is smaller than the actual difference in engine output.
This is followed by a vague statement about "tanks powered by 1,500 hp engines" not performing better; the author failed to clarify if he meant in regards to efficiency, absolute net horsepower available or in regards to cross-country performance.

The Challenger 1 is based on the Shir Iran 2 main battle tank designed for Persia. According to British data, the Shir (Iran) 2 prototype's armor offered protection comparable to only 325 mm steel at the frontal arc. The British military desired a higher level of protection, but it is questionable how much better the actual production version was. If you look at the power to weight ratio of the Shir 2, you'll notice that it should weigh about 63-65 metric tons - like the Chieftain-based Shir (Iran) 1, the second version was also fitted with the Condor Perkins V12 engine developing 1,200 hp.
There is quite some time between the date of the document (1978) and the introduction of the Challenger 1, so they could have adopted a new generation of Burlington armor or at least chosen to integrate another variant, which was more optimized against KE. However I think your "620 mm RHAe for a LOS thickness of up to 850 mm" is a rather far stretch: the desired protection for the MBT-80 was to resist 125 mm APFSDS at distance along the frontal arc (est. penetration 445 to 460 mm at that range). The table lists the MBT-80 with a protection level of 430(+) mm. I think this should give us a ballpark estimate for armor protection.
Please note that the MBT-80 was expected to achieve such a high level of protection thanks to the usage of aluminium armor for the rear section of the vehicle, an idea that the British FVRDE was very fond of, as various other projects show (older projects such as the Chieftain Mk 5/2, FV 4211, JagdChieftain, and Vickers Valiant used full hulls/turrets made of aluminium). The Chieftain is a very heavy tank for its day, so one should expect a high level of protection; but it is also very large with a rather heavy gun. The British themselves claimed that the M1A1 HA has better protectiton at the frontal turret arc than the Challenger 2 prototype design from 1988, which was supposed to offer improved protection over the Challenger 1.
I don't know where you are getting the values for the armor thickness and protection of the M1 Abrams and M1A1/M1A2 model. I know that there are a lot of different armor thickness values floating around, but none of them are confirmed. These are either "guesstimates" or based on scale measurements done on drawings. These are not very accurate. I remember a discussion with Damian back on DFI, where he claimed the M1A2 has 960 mm thick armor. Measuring the drawing from Hunnicutt's "Abrams: A History of the American Main Battle Tank" which he provided, resulted in an armor thickness of less than 800 mm. He then added his own lines where the armor modules would end, because the sketches in Hunnicutt's book are rather inaccurate (I agree with this - the weldlines do not represent the actual armor). However based on his new lines (which IMO extended a bit too much into the tank) the armor thickness would have been 820-840 mm on the left and 880-900 mm on the right side (depending on wether the pixels of the lines were included or not). Then another poster joined the dicussion, who had created a 3D model of the M1A2 Abrams. He came to the conclusion, that both front modules of the turret were only 845 mm thick, but the backplate extended even further into the turret than on the altered drawings from Hunnicutt...
Over the years I've seen thickness values for the Leopard 2A4 ranging from 500 to 900 mm (we've gotten a confirmation that it's ~860 mm), from 600 to 800 mm for the M1 Abrams and from 750 to 1,000 mm for the M1A2... given that range I'd be rather careful to base armor protection estimates on "guesstimated" thickness values. Aside of statements from Zaloga, I've yet to see actual proof that the physical thickness on the M1IP/M1A1 was increased over the M1 Abrams.
I don't know where you got the 440 mm RHAe vs KE for the M1 Abrams. The CIA document from 1982 revealed that "one version" (which we just assume that it is the basic model - in theory it could have been the design for the M1IP/M1A1: the M1E1 prototypes with weight demonstrators to resemble the armor package then in the making were delivered in March 1981) had 400 mm RHAe vs KE at the turret; there is no statement made regarding wether this protection is achieved along the frontal arc or this is just achieved when the turret is directly hit from the front. In theory both the British and the CIA estimates could fit together, with the turret achieving 340 mm steel-equivalent protection when hit at a 20-25° angle (nullifying the slope along the horizontal axis) and 400 mm steel-equivalent protection when hit directly from the front.
Given that composite armor elements such as NERA panels, STEF, glass and ceramic tiles provide different protection at different angles, it could very well be that the efficiency increases with at larger impact angles (and thus lowered thickness) to provide a more consistent level of protection.
For the M1A1, I think we can use the M1 Abrams' armor protection as a basis and use the weight simulators of the M1E1 as a reference how much armor weight was added. Given an anti-KE mass efficiency of 1 to 1.5 (based on British documents on the development of Chobham), the M1A1's armor protection could be estimated.
The export M1A2 has 600 mm vs KE for the turret armor along the frontal arc. If we assume that the armor efficiency stays the same regardless of angle, that would be 640 to 660 mm from the front (depending on which side of the turret front is hit due to their different angles).
As for your model of the Leopard 2: I don't think it is very accurate. According to the Swedish documents, last slide, about 20% of the Leopard 2's frontal projection reach 400 mm RHAe vs KE or higher; in your drawing it is roughly 17% of the turret only. Given that the hull has a similar surface area, I think you should at least double the area with 400+ mm steel-equivalent protection vs KE. But due to the fact that the protection provided by composite armor depends on the specfici interaction between armor array and penetrator, I personally wouldn't want to use singular values for armor protection.
Early Soviet APFSDS ammo (and some NATO types like M735) was really, really bad at defeating everything other than a simple steel plate. The DM13 was specifically optimized to defeat multiple spaced steel plates, because the earlier APFSDS ammo designs (used for the M735 and the MBT-70's APFSDS ammo) couldn't do that.
The above is a composition from various sources, so I wouldn't rate that reliable. First of all the drawing used by Hilmes didn't include a backplate (it was censored), so the line drawn in the photo is not really accurate. IRL the thickness of the center plate is parallel to the outer plate - it only gets thinner at the top (where the slope is increased to provide sufficient protection against older types of ammo) and at the lower section (where the tank is less likely hit). The image section showing the turret is from a patent regarding a new recoil mechanism, which would sit within the left and right corner of the turret, rather than on the gun. This would require redesigning the complete turret, so I wouldn't necessarily consider that a reliable source. There are also patent drawings showing a cicrcular hole in the armor for the EMES-15, we know that this is not true.

It might be the same type of logic used to defend the Merkava 3's 1,200 HP engine compared to the 1,500 HP AGT-1500C: the transmission is more efficient than the previous model, so that it can deliver more performance out of the 675 HP engine to the drive sprockets than the old transmission could extract out of a 800 HP engine. I.e. the old transmission would loose something like 150 HP out of 800 (thus effectively having 650 HP at the drive sprockets), while the new transmission would only loose 25 HP.
The same argument was being made by some IDF soldier in the ARMOR magazine quite a while ago - i.e. the Merkava 3's 1,200 HP would come a lot closer to the AGT-1500C due to the higher efficiency of the Renk 304S tansmission. Given that Hunnicutt claims that there are 1,232 net horsepower available in case of the Abrams', this statement was probably exaggerated.

I think this is a rather optimistic colorization on the model. If the documents from Sweden have shown anything, then it should be that achieving a consistent level of armor protection is nigh impossible. The red area on the hull extends to the floor plate - there shouldn't be any composite armor at all. Furthermore the upper edge of the armor modules likely (due to the reduced thickness along the line of sight) won't achieve the same level of protection - that's at least the case in the Swedish computer analysis of the different turrets. The gun mantlet armor module is very thin, so I'm not sure if this should be able to achieve the same protection level as the turret armor (even at 30° impact angle the turret will be thicker.
Defeating the JM33/DM33 APFSDS at 250 metres requires just 530 mm of armor steel or a special armor array providing equivalent protection. The Leopard 2A4 production model from 1991 supposedly has armor providing about 550 mm steel-equivalent protection at 50% of the tanks surface along the frontal aspect. The Type 90 being designed at the same time (being lighter, but also significantly smaller) achieving a similar level of protection to the contemporary Leopard 2 variant seems plausible.

I've been wondering about the protection difference between the Swedish version and the German version. What I found very odd is the table on the last slide I originally posted, which list the Leopard 2 Improved with Vorsatzmodule of the generation "D-2" and internal armor of the generation "B".
I think this might be a reference to which prototype was send to Sweden for tests. The original Leopard 2 Improved prototype was the Komponentenversuchsträger (Leopard 2 KVT; "component test bed"), which was based on the chassis number 20825 (the 825th tank made by Maschinenbau Kiel). Based on this number, it appears that the hull (and turret) were made as part of the 6th Leopard 2 batch (the second batch of 2A4 tanks) made between January of 1988 and May of 1989. The previous batch (batch number 5, first batch of Leopard 2A4 tanks) was produced between December of 1985 and March of 1987, while the last batch of Leopard 2A3 tanks ended with the chassis number 20644 for MaK. Given that 45% of all German Leopard 2s were made by MaK and the 5th batch consisted of 370 tanks; therefore I assume that the 5th batch ended with the chassis number 20810 or 20811. The first 96 tanks of the sixth batch were made with the old armor, therefore the chassis number 20825 would fall into that category.
The later Leopard 2 Improved prototypes (Truppenversuchsmuster Maximum and Truppenversuchsmuster Minimum, "troops trial model maximum/minimum") were based on the chassis numbers 11156 (TVM max) and 11157, which were made by Krauss-Maffei and belonged to the 8th batch (the last batch of tanks for the German Army) made between January of 1991 and March of 1992.
This would mean that original KVT (later renamed IVT) used 1st generation composite armor (also confirming that the "B" in the table stands for the original composite armor), while the TVM tanks had 3rd generation armor (believed to be "D-1", "D-2" or "D-3" in the table). The actual Leopard 2A5 and Leopard 2A6 tanks were made using hulls from the 6th, 7th and 8th batches - so all German tanks with the second and the third generation of composite armor + 22 tanks with the original hull armor package. If the hull armor wasn't altered (although I assume it was), this would mean that there would be some tanks with worse/better hull armor than the others...
The turrets were all taken from the 1st batch, so they probably replaced the armor inserts and upgraded them to "C" or "D-1/2/3" level. According to the book by Scheibert, the armor modules in the turret were replaced.
According to one issue of the Waffen-Arsenal magazine ("Leopard 2 A5 - Euro-Leopard 2" by Michael Scheibert), the Leopard 2 tested in Sweden was either a KVT/TVM mix or they tested both variants (not written clear enough for me to understand what was the case). In theory this might mean, that the higher level of protection of the Swedish variant is just the result of using "C" or "D-1/2/3" level armor inserts with the same Vorsatzmodul.
Yes, that's true. However I've never seen a cast turret with composite armor in the gun mask and Soviet gun masks tended to be thinner. Also the composite filler of the turret always ends a few centimetres away from the gun mount.

It depends on which armor package the Norwegian Leopard 2A4s are fitted with; the armor packages from 1987 and 1992 (or at least this is what I think the graph shows) would still be able to withstand older Soviet/Russian APFSDS ammo at long ranges. Don't forget that the majority of the Russian tanks seems to rely on Vant and Mango. Only the newer vehicles (T-90, T-90A and Sprut-SD) and upgrades (like the T-72B3) can utilize higher penetration APFSDS. So its still "good enough" to deal with the majority of the older tanks and IFVs. Now that the BMP-2 will receive Kornet and the T-72B3 is being adopted in larger numbers, it is time to upgrade.
If the CV90 -120T is not fitted with an active protectiton system, then it is not really better than the Leopard 2A4. It is a larger target (higher hull and turret, wider hull), while probably providing similar mobility and less protectiton. Only the lighter weight and the more advanced FCS make it superior. Buying an armor package (AMAP) and adding new electronics seems to be a much better idea IMO.
That the Leclerc wasn't well armored is no surprise, given its state of development (being pretty much a prototype during the tests) and its turret layout. I have mentioned the weak gun mantlet and the "gun bulge" in the turret roof several times, see the very first post of this topic. When seeing the tank from the front, it will have a lower profile, but not from the side. At the 20° angle, the Leclerc needs to protect 1.7 m² (for a crew of 2), while the Leopard 2 needs to protect only 1.6 m² (with a crew of 3!). That's quite surprising IMO. The later Leclercs feature thicker and heavier armor packages, so they probably closed the gap...
(from the Steel Beasts forum):
They also added an armor block at the gunner's sight (left - old prototye, at the right is a newer model):
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Forgot to make a screenshot of the T-80U's armor, but Andrei_bt already made one:
That's the doownside of cast turrets with ERA...
PS: Also confirms DM33 penetration to be 470 mm at 2,000 m distance, 540 mm at 200 m distance.

Wow,. thank you @skylancer-3441. Seems like R. Lindström (accidentally?) uploaded some (formerly?) claissified documents in his original presentation. That confirms that the diagram is real, @Militarysta
M1A2 turret was also meant to receive add-on armor...
Leclerc armor was very poor:
Leopard 2 armor evolution:
Turret front of a Leopard 2A5 is about 700-800 mm vs KE, 1,600 to 1,800 mm vs HEAT. The Swedish Strv 122 has a different armor package, providing higher protection levels; the Leopard 2 (flat turret) has 300 - 500 mm vs KE protection, but about 50% of the surface is protected against APFSDS ammo with less than 400 mm penetration into steel only.
Note the last slide: The German prototype offered to Sweden (and maybe also the German tanks) have Pakete (integrated armor pacakges) of the technology generation "B", while the Vors. Modul (Vorsatzmodul, add-on module in front of the armor) has the technology generation "D-2". I suppose Sweden uses a more modern integrated armor pacakge (C, D-1, D-2, D-3) and the same Vorsatzmodul. The German wikipedia (without citing a reference) claims that the German Leopard 2 uses "C technology" armor (so "Pakete"). Maybe that's based on Spielberger's book, I need to take a look at it in the future. The graph in the center of the last slide shows five colors... my guess (based on the graphs at the left and the right:
purple - Leopard 2 from 1979, armor package of the "b" generation (fits the graph on the left);
red - Leopard 2 with enhance armor package (1987), which might be "C" generation;
yellow - Leopard 2 with enhanced armor package (1992), which might be "D-1" generation;
blue - Leopard 2 with armor of the "D-2" generation or armor of the "B" generation with Vorsatzmodul of the "D-2" generation
green - Leopard 2 with armor as adopted by Sweden - so probably "C" or "D-1/2/3" base armor with Vorsatzmodul of "D-2" generation
This would lead to the following protection estimates (please note that it says frontal arc - +30° to -30°, not direct from front):
Leopard 2 - 2A4 (from 1979): 300 mm protection vs KE at 60% of the surface, 400 mm protection vs KE at 25% of the surface
Leopard 2A4 (from 1987): 300 mm protection vs KE at 65% of the surface, 400 mm protection vs KE at 55% of the surface, 500 mm protection vs KE at 30% of the surface
Leopard 2A4 (from 1992): 350 mm protection vs KE at 93% of the surface, 400 mm protection vs KE at 87% of the surface, 525 mm vs KE at 50% of the surface and 620 mm vs KE at 42% of the surface
Leopard 2A5 (prototype?): 620 mm protection vs KE at 65% of the surface, 700 mm protection vs KE at 40% of the surface
Leopard 2A5 (production model? Swedish model?): 700 mm protection vs KE at 75% of the surface
That also confirms that the older Leopard 2 models didn't feature the enhanced side armor found on newer production variants:
Btw: "gor" seems to be pentrated, "ub" means to be not penetrated in one of the earlier tables.

Are you sure? Is it confirmed to be fake?
This is from a presentation by R. Lindström, who works/worked for the Swedish FMV:
Except for the values, everything is there (lower left corner). The same set of presentations includes a lot of 100% valid files:
So overall the drawing seems to be valid. Maybe the guy photoshopped the drawing into the background of a FMV file and added his own values - but look at the drawing in the left corner of the first slide: this drawing does exist and it does have oddly placed text... maybe because R. Lindström wasn't allowed to post the true version (which would have protection values there?)...

No, only at the turret front. The volume is a limiting factor, if you want protection against large calibre KE rounds and tandem shaped charges. Just look at the Leclerc (armor thickness increased on later variants), T-84 (armor thickness increased compared to T-80UD) and Leopard 2A5/Evolution/ADT/MLU (all adopting external armor modules, because the frontal armor doesn't have enough volume).

Here are two quotes from Rickard's O. Lindström's article on the development of the Strv 2000, which might be relevant to the protection level of NATO tanks in the 1990s:
The above statement is made regarding the development of the Soviet 125 mm APFSDS ammo: NATO tanks of the 1980s doesn't seem to be protected against the weapons/ammo used by Warsaw Pact tanks. This probably meant that the protection of the tanks tested in Sweden wasn't necessarily as high as usually estimated on the internet...
Inspired by the M1A1 HA, the Swedes tested DU as possible armor material for the Strv 2000 tank project. It showed that the usage of DU increased protection, but only if the volume was the limiting factor. If the weight was the limit, other materials could reach similar (or higher) protection.

Maybe, maybe not. There might be aswell an American XM711. Don't forget that the designation "M426" exists in the US inventory (105 mm HEAT-FS round) and the Israeli inventory (105 mm APFSDS-T round, also known as 105 mm DM63); it would be quite a coincidence, but there also might be an American XM711 round. Maybe the M711 was developed as a joint-venture with US companies or based on a contract of the US Army?
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Enough of the "heavy" discussions, time to lighten up the mood. French armor protection (some of the other forum users with better French skills should try to fact-check my translation):
AMX-32:
frontal armor consists of spaced armor, the outer layer is a dual-hardness steel plate; spaced armor is also used on the turret sides
designed to resist 57 mm AP (from the ASU-57) and 75 mm APCBC ammo (from the AMX-13/75) - penetration should be 100-170 at 1,000 m distance
a lot better protected than the AMX-30, which was designed to stop 20 mm ammo only
roof armor is designed to provide protection against bomblets with 30° impact angle (?)
AMX-40:
frontal arc is protected by composite armor, which is resistant to 76 mm AP ammo - only the PT-76 and M41 Walker Bulldog used this calibre - and the RPG-7
side armor of the turret is spaced and provides protection against 23 mm AP
AMX E4 (modified AMX-40 design offered to Egypt, weight increased from 43.7 metric tons to 50 metric tons):
completely redesigned (composite) armor, offers protection against 105 mm HEAT and APFSDS ammo at the frontal arc
heavier versions (53 metric tons) of this design were supposed to have armor protection comparable the Leopard 2(A4)
AMX Leclerc:
unlike Chobham, the Leclerc's armor was always designed to provide higher efficiency against both KE and CE threats (early Chobham was optimized against hollow charge ammunition only)
the Leclec has the same weight as the Leopard 2A4, but is 850 mm shorter (hull length). This allows the implementation of a higher protection level. However instead of focusing all armor on the frontal arc (like the Leopard 2), the weight was used to increase protection along a greater area: the heavy ballistic skirts are thicker and cover more surface, while the turret side (and bustle) armor is designed to protect against RPGs.

The articles are surely interesting to read, but they do not say that armour was not tested in the United States. The actual tanks did not have armor, but the documents also mention that Germany delivered a ballistic turret (steel shell with armor modules) and a ballistic hulll (steel shell with armor modules) to the United States for testing:
The tanks also weren't x-rayed:
But the statement regarding the XM1 being better protected than the Leopard 2AV also should be taken catiously. According to the document, the protection was not solely limited to an analysis of the armor, but also included stuff like ammo storage (where the Chrysler XM1 is better) and other factors:
The only odd statement is the following:
"The Leopard has 87 percent less special armor protection than the XM1". That would mean - if this was a statement regarding the quality of the armor - that the Leopard 2AV's protection would be worse than the Leopard 1's (!). 13 percent of 350 to 400 mm is less than 60 mm. Therefore we can say: this value does not relate to actual armor protection.
Instead it seems to be related to armor coverage:
The Leopard 2AV did not have special armor skirts (only the same skirts as the Leopard 1), it doesn't have composite armor at the turret bustle (only simple spaced solution also used on the Leopard 2) and it's hull armor had reduced special armor thickness (because it incorporated a fuel tank following a suggestion from the United States, that this would be an efficient armor layout). So IMO the XM1 was found to have much more surface covered by special armor:
The document "Department Of Defense Consideration Of West Germany's Leopard As The Army's New Main Battle Tank" seems to support this suggestion and is a lot more balanced (it criticizes the fact that biased people like Gen. Robert Baer, the XM1's project manager, were part of the "judges" overseeing the tests). It states the following regarding the armor:
"... special armor protects a larger area of the XM-1 than the present Leopard ..." - no surprise, it has heavy ballistic skirts, turret bustle armor and probably also more special armor in the hull.
"... and that the XM-1 is currently capable of sustaining more types of hits without serious damage." - well, the Leopard 2AV would probably fail to stop a 81 mm HEAT round (Carl Gustav warhead) at the turret bustle... just like the Leopard 2A4 or Leopard 2A5...
Reason for the different protection levels provided by the armor are attributed to "Differences in how the two countries perceive the threat." - IMO this means, that Germany focused more on protection against KE threats (i.e. APFSDS ammo and artillery fragments) rather than shaped charges. This would fit the graphic posted earlier.
"The protection offered by the present-generation German chobham armor is not [...] equal to that of the XM-1." - it was apparently also optimized to defeat other threats. Furthermore the hull armor (incorporating a fuel tank) was extremely inefficient! According to German documents, redesigning the hull with a single array of NERA (rather than two separate ones?) allowed to free 700 kilograms of weight without reducing the armor protection:
Well, there are three facts to remember:
1. The Leopard 2A4's turret armor was tested with a physical thickness of 800-860 mm against the LKE1 APFSDS, so it simulated a direct hit from the front. The M1A2 armor scheme shows only the guaranteed protection along the frontal ± 30°. So the 600 mm RHAe value might be 650-700 mm RHAe when hit from the front (0° from the turret centerline). The 350 mm hull armor however should be corresponding to 0° impact angle, because the effective armor thickness increases at other angles.
2. The T-80U's turret in Sweden was claimed to provide protection equal to roughly 600 mm RHAe vs KE (without Kontakt-5 ERA)
3. Leopard 2A5 was considered to be better protected than the M1A2, Leclerc and T-80U in Sweden and in Greece.

The side armor at the turret bustle (the section providing 380 mm protection at 90° impact angle) is thicker than the armor at the crew compartment:
So it seems the side armor has a thickness of about 300 mm at the crew compartment, while the thickness at the bustle is about 400 mm. The armor seems to have different composition depending on location:
The bustle armor consists of many sloped NERA plates, while the NERA plates at the side armor of the crew compartment are flat (so they require an angle to achieve a higher level of protection):

Well, I didn't mean the armor of current tanks, but older variants. Some claim that the M1A1HA has 600-700 mm steel equivalent hull armor vs KE and 800 mm steel equivalent turret armor vs KE. I do believe a lot of modern tanks have similar protection levels - the German Leopard 2A5 and 2A6 tanks made use of Leopard 2A4 hulls, so the protection is probably about 300-450 mm vs APFSDS ammo. When fitted with applique armor (or newer inserts), the protection level should be higher.
Swedish tests using the MEXAS-H armor (on the hull aparently a single heavy NERA sandwich with lots of slope) from IBD Deisenroth (locally made by Åkers Krutbruk under licence) showcased an increase in armor protection by 50 to 100% in case of the M1A1 hull. This armor is also fitted to the hulls of more modern Leopard 2 variants (incl. the Strv 122). The Leclerc was to be fitted with a wide array of MEXAS armor (turret front armor similar to the Leopard 2A5, side armor similar to the Leopard C2 from Canada).
The Leclerc was some paper design utilizing the MEXAS armor, it probably was not very optimal. I guess the turret needs to be turned to the side, just like on some Leopard 2 variants.

This is identical to the diagram I posted earlier (with a lot less pixels) coming from a presentation on the Swedish tan trials. It seems that the protection level was censored in the Swedish presentation (because it is public access). I guess somebody dug this up out of the Swedish archives? But the file name suggest that it shows the M1A1 HA...
That said, it seems to be legit. It would confirm my believes on the armor protection of modern tanks being hugely exaggerated and matches some of the earlier mentioned requirements stated in the British documents.
PS:
This is another photo from a Swedish presentation. Note how the background matches!

That's very interesting, but using a single value to represent armor protection is quite a bit lackluster. What exactly is one value meant to show (average protection, maximum protection, protection at the frontal arc, protection at the frontal surface only)?
The British underestimated the armor protectiton of Soviet tanks by a lot. T-64 and T-72 should have some 350 mm RHA equivalent armor on the UFP and turret armor up to 450 mm. The T-72A, T-80(B) and later tanks would have even higher levels of protection.
The Leopard 2's armor value is suprisingly low. It makes me wonder what the British military knew about the Leopard 2 in 1978. Previously there was quite a bit of cooperation (UK presenting Chobham to Germany in 1970, Germany and UK developing a tank in 1972-1976/77), but the latter all ended about the time the Leopard 2 was redesigned to accept special armor. The Leopard 2K has 38 mm high-hardness steel + 127 mm airgap + 84 mm RHA sloped at 25° at the turret front, which turns out to be 288.6 mm steel along the line of sight. So assuming a slightly higher efficiency than RHA (due to it being spaced armor with high-hardness steel), it already should reach protection equivalent to 300 mm steel armor against APFSDS ammo (at 0° impact angle). I'd be quite surprising if the Leopard 2 retained this level of KE protection (with a greater coverage) on the 2AV and later models...
The Shir 2 has a power-to-weight ratio of 18 bhp/ton with the 1,200 hp CV12 engine, so it should weigh something between 63 to 65 metric tons... that's quite a bit of weight given the poor level of protection. The Shir 2 was used to create the Challenger 1 (!), which has a weight of only 62 metric tons. Unless the armor composition was changed, this would mean the Challenger 1 had the lowest KE protection per weight (although it is not exactly clear how the protection was defined) and be worse protected than the M1 and M1A1 Abrams.
This graphic was published in a 1986 German book. The Leopard 2 is meant to resist (at the turret) a 125 mm APFSDS at 1,500 m range. That sort of makes 300 mm RHA impossible, unless this is a minimum or average value (though the latter would mean, that the hull would have less than 300 mm RHA equivalent protection, which also doesn't seem realistic...).